linux-kernel - Re: [PATCH 3.10 12/27] x86-64, espfix: Dont leak bits 31:16 of %esp returning to 16-bit stack

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Message-ID: <20140806151620.GD12150@hercules>
Date:	Wed, 6 Aug 2014 16:16:20 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Brian Gerst <brgerst@...il.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Borislav Petkov <bp@...en8.de>,
	Andrew Lutomriski <amluto@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dirk Hohndel <dirk@...ndel.org>,
	Arjan van de Ven <arjan.van.de.ven@...el.com>,
	comex <comexk@...il.com>,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH 3.10 12/27] x86-64, espfix: Dont leak bits 31:16 of %esp
 returning to 16-bit stack

On Tue, Aug 05, 2014 at 11:14:04AM -0700, Greg Kroah-Hartman wrote:
<...>
> @@ -188,17 +193,21 @@ static void note_page(struct seq_file *m
>  		/*
>  		 * Now print the actual finished series
>  		 */
> -		seq_printf(m, "0x%0*lx-0x%0*lx   ",
> -			   width, st->start_address,
> -			   width, st->current_address);
> -
> -		delta = (st->current_address - st->start_address) >> 10;
> -		while (!(delta & 1023) && unit[1]) {
> -			delta >>= 10;
> -			unit++;
> +		if (!st->marker->max_lines ||
> +		    st->lines < st->marker->max_lines) {
> +			seq_printf(m, "0x%0*lx-0x%0*lx   ",
> +				   width, st->start_address,
> +				   width, st->current_address);
> +
> +			delta = (st->current_address - st->start_address) >> 10;
> +			while (!(delta & 1023) && unit[1]) {
> +				delta >>= 10;
> +				unit++;
> +			}
> +			seq_printf(m, "%9lu%c ", delta, *unit);
> +			printk_prot(m, st->current_prot, st->level);
>  		}
> -		seq_printf(m, "%9lu%c ", delta, *unit);
> -		printk_prot(m, st->current_prot, st->level);
> +		st->lines++;
>  
>  		/*
>  		 * We print markers for special areas of address space,

Hmm... the original commit has a 2nd hunk here that does seem to be
applicable to 3.10.  Was this dropped accidentally or on purpose?

Cheers,
--
Luís

> --- a/init/main.c
> +++ b/init/main.c
> @@ -606,6 +606,10 @@ asmlinkage void __init start_kernel(void
>  	if (efi_enabled(EFI_RUNTIME_SERVICES))
>  		efi_enter_virtual_mode();
>  #endif
> +#ifdef CONFIG_X86_64
> +	/* Should be run before the first non-init thread is created */
> +	init_espfix_bsp();
> +#endif
>  	thread_info_cache_init();
>  	cred_init();
>  	fork_init(totalram_pages);
> 
> 
> --
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